Yesterday I had a talk with a good friend of mine which I ´ve grown up with, had not seen him in ages.

Anyways by coincidence we started talking about our profession, turns out he is a BMW Mechanic.
So eventually we started talking about our cars, then he asked me if I still run on the oil BMW has filled the Z up with. "Of course" I responded, of which he replied "Get Rid of that Crap asap".

He continued "It is not the worst oil, but by far not the best either. All of my colleagues who drive BMW´s ditched this crap as well."

When I asked him how they came up with that, he said that when you disasemble as many engines as they do on a regular basis, you tend to pull conclusions based on the way how the engines look.

That sounds kinda comprehensible, and he suggested to go with Mobil Oils. Mobil 1 ESP Formula 5W30 to be precisly, and he offerd to swap it for me, no charge

Mobil 1 5W30 is frequently recommended by BMW enthusiasts for those that like to DIY oil changes. Used it in both E46 3ers and X5 that I've owned. Sourced inexpensively from walmart. No issues whats so ever. Would have used it in the M3 but it required different weight.

I always use Castrol Edge 5W30, because that is the best they have on stock at the Chinese BMW dealerships. From what I have read it is a great oil, but it is of course hard to know for sure. I feel fairly certain that it is over-priced in the same way that a Gucci bag is over-priced, but I just don't feel comfortable selecting anything cheaper.

I am also afraid that if I buy anything from anywhere else, it will be counterfeits. Probably not as big a problem in the US though...

Here I do not even fully trust BMW. I always ask them to hand over the empty bottles after an oil change. Not that I know how to identify counterfeits just from looking at the bottles, but at least I can check if they actually used Edge and 5W30, and not whatever was first on the shelf.

Mobil 1 ESP Formula 5W30 to be precisly, and he offerd to swap it for me, no charge

Did anyone else ditch the OEM - Oil?

I am not so sure about the Mobil 1 5W30. I used that and Mobil 1 10W30 in my WRX and did oil analysis through blackstone labs and found that the oil sheered down to a lower viscosity after only 4000 miles and there were a lot of traces of wear metals in the oil.

My oil consumption was higher as well. I don't believe Mobil 1 5W30 is appropriate for a high heat turbo motor such as our N54

I switched to Castrol European Formula 0W30 and subsequently to Shell Rotella T and those were much more sheer stable under high temps and my oil consumption normalized, and wear metals in the analysis report reduced

Right now in my Z4 35i I am using the OE oil but if I were to switch, I would go back to European Castrol 0W30. There is a forum called bobistheoilguy where there is so much tech on oil, and this oil was highly regarded.

Coincidentally, BMW USA calls out specific oils that are approved for the engines and European Castrol 0W30 is one of them.

With no disrespect meant to the OP's mechanic friend, I would really want some strong tech before moving away from the manufacturer's recommendation. One example of such tech would be used oil analysis reports of the oil being recommended for the specific motor for a decent period of time from someone with similar usage pattern as you.

I tested both Castrol and mobil 1 0w30. There was no significant difference, but mobil 1 seems to idle so well, you can't even tell the engine is on. No ticking sound coming from the engine. Castrol still has a dark honey hue color while mobil 1 is darker after changing the oil 8500 miles. IMO you can't go wrong with either, but i run castrol 0w30.

hard to find Castrol European Formula 0W30 here in Toronto. I did try with no luck. I plan to run Castrol Edge 5w-20 in the winter here and swap them out come the summer. Any one knows any reasons I shouldn't do that?

Here's an article from a very knowledgeable Oil expert, "Dr. Haas is a physician and surgeon. He graduated from the University of Florida with a degree in biochemistry with honors. He studied motor oils since high school where he did independent studies on this topic. He studied the properties of viscosity. "

After taking 2 days to digest the article, I chose to adjust my beliefs to his data, and go with a thinner oil rather than thicker. My winter drives rarely gets up to operating temperature and thinner oils seems to suit my immediate needs better.

I am not so sure about the Mobil 1 5W30. I used that and Mobil 1 10W30 in my WRX and did oil analysis through blackstone labs and found that the oil sheered down to a lower viscosity after only 4000 miles and there were a lot of traces of wear metals in the oil.

My oil consumption was higher as well. I don't believe Mobil 1 5W30 is appropriate for a high heat turbo motor such as our N54

I switched to Castrol European Formula 0W30 and subsequently to Shell Rotella T and those were much more sheer stable under high temps and my oil consumption normalized, and wear metals in the analysis report reduced

Right now in my Z4 35i I am using the OE oil but if I were to switch, I would go back to European Castrol 0W30. There is a forum called bobistheoilguy where there is so much tech on oil, and this oil was highly regarded.

Coincidentally, BMW USA calls out specific oils that are approved for the engines and European Castrol 0W30 is one of them.

With no disrespect meant to the OP's mechanic friend, I would really want some strong tech before moving away from the manufacturer's recommendation. One example of such tech would be used oil analysis reports of the oil being recommended for the specific motor for a decent period of time from someone with similar usage pattern as you.

Reffering to their Homepage the Oil is BMW Longlife 04 certified.
According to the Z's owners Manual you can use Oil that is either BMW Longlife 01 or Longlife 04 Certified.

Now is there any difference? 04 is the newer standard, replacing the 01 to meet environmental regulations. 04 oils are "greener" than 01 oils hence there is less phosphorus and sulfide in it (substances used to reduce friction) can anyone confirm this? Alternatively I may use Mobil 1 New Life 0w40 which has BMW LL 01 certification.

Reffering to their Homepage the Oil is BMW Longlife 04 certified.
According to the Z's owners Manual you can use Oil that is either BMW Longlife 01 or Longlife 04 Certified.

Now is there any difference? 04 is the newer standard, replacing the 01 to meet environmental regulations. 04 oils are "greener" than 01 oils hence there is less phosphorus and sulfide in it (substances used to reduce friction) can anyone confirm this? Alternatively I may use Mobil 1 New Life 0w40 which has BMW LL 01 certification.

Thanks for the constructive comments so far!

My understanding is that LL04 is for low or no sulphur content fuel countries (EU) and LL01 is for high sulphur content fuel countries (such as US). Also, check out the list of LL04 oils. I think they are pretty hard to find in the US.

hard to find Castrol European Formula 0W30 here in Toronto. I did try with no luck. I plan to run Castrol Edge 5w-20 in the winter here and swap them out come the summer. Any one knows any reasons I shouldn't do that?

It is a 20 weight vs 30 weight or 40 weight recommended by manufacturer and isn't on the list of approved oils.

Of those 2 reasons, the first makes me personally more leery.

I think you should spend for oil analysis if you go that route. It's the best way that I know to bring data to decisions like this one. I wouldn't lean on marketing claims or general advice when it comes to oil.

I have filled up my fiance´s 125i with Mobil 1 0W40, it will be my testmule

It may be not very objective, but I could have sworn that the engine now runs smoother than with the OEM Oil.
Although the oil has been changed on a regular basis, when I opend the Refill-Cap ontop off the engine, it was completely coverd with kinda big lumps of oil.
Cold starts now seem to be "easier" for the engine too. I´ll keep you updated

So went to my local BMW dealer to have my engine oil + filter changed today. I specifically asked for 5W30 Castrol Edge and stated that I would like to keep the empty bottles after the job was finished.

We added a few more service items to the joblist, and then they started working on the car. As I later went to have a look inside the workshop, I found that they had just emptied the engine for its old oil, changed the filter and were moving a barrel of Castrol oil towards my car.
As I looked closer, I found that it was a barrel of 0W40 oil. I complained, and they instead found 7 x 1L bottles of the right oil...

So went to my local BMW dealer to have my engine oil + filter changed today. I specifically asked for 5W30 Castrol Edge and stated that I would like to keep the empty bottles after the job was finished.

We added a few more service items to the joblist, and then they started working on the car. As I later went to have a look inside the workshop, I found that they had just emptied the engine for its old oil, changed the filter and were moving a barrel of Castrol oil towards my car.
As I looked closer, I found that it was a barrel of 0W40 oil. I complained, and they instead found 7 x 1L bottles of the right oil...

I'm pretty sure it's well known that BMW oil is the same as Castrol Edge Euro oil. there was a thread I started a while back and some one proved this to be the case.
If you care to read, here's link to a technical description of different grades of motor oil: http://www.upmpg.com/tech_articles/motoroil_viscosity/. It speaks favorably about Mobil 1 Euro 0W-40, which happens to be a BMW approved oil.

Do a used oil analysis for the OE oil and replacement aftermarket oil under the same oil change interval and usage pattern.

Great way to let you know whether or not the change in oil was beneficial through the change in trace wear metals, remaining additive package and physical characteristics of the oil (i.e. whether or not oil sheared down to a lower viscosity)

Anyway, the service sheet said they used Pennzoil Synthetic. When I asked the service manager about it he said their bulk oil is Pennzoil Synthetic though if you buy individual quarts from them it is Castrol Syntech.

I specifically asked him if the Pennzoil meets warranty specs and he of course said yes.

In my experience with other cars Pennzoil oils have been as good as any other and generally less expensive.